Hot water heating system



March 7, 1944. E. B. TIDD HGT WATER HEATING SYSTEM Filed May 21. 1942 Patented Mar. 7, 1944 UNITED STATES PATENT OFFICE nor ws'run Burma srsrm'r Edwin B. Tidd, Mount Prospect, Ill., assignor to Bell I; Gossett Company, Morton Grove, 111., a corporation of Illinois Application May 21, 1942, Serial No. 443,902

is Claims. (Cl. 237-19) ators and an expansion tank which is connected directly to the top of the boiler or to the radiator supply line by a relatively small pipe, usually having a diameter of the order of one-half inch. The valve prevents'thermo-gravitational flow to the radiators during the summer season, or at other times when heat is not wanted in the radiators, and is opened by pump pressure in response to heat demands.

In systenis of the above character which are hand or stoker fired and in which the boiler water is accordingly subjected to continuous heat, the operation of the pump is controlled by a room thermostat which is responsive to the demand. of the associated space for heat, or by a boilerl. aquastat which serves as a high limit and safetyswitch and closes the circuit to the pump when the temperature of the boiler water reaches a predetermined maximum. For a space heating demand, the pump produces a beneficial heating eilect in the radiators, but when the pump is placed in operation by the aquastat, the excess heat of the boiler water is dissipated through-the radiators so. that abnormal heating of the boiler water is prevented.

An important operating objection to such a system is that in the event of pump orelectric power failure, the flow control valve will not be opened and the temperature of the boiler water will begin to rise. This rise may be accelerated by the fact that the valve in the supply line confines the boiler water to a relatively small space.

Moreover, the failure of the electricpower may continue unnoticed for such a time that the boiler water reaches a dangerous temperature, or may begin to steam. In any event, overheating of the boiler water presents a serious operating-and economic problem because where the service water is indirectly heated to atemperature in excess of 140 Fahrenheit, deposits of lime and sediment are formed rapidly in the coils or tubes of the heater in numerous localities, thus reduc ing the rate of heat exchange and lowering the temperature of the water available at the service outlets. This liming condition is continuously aggravated by recurrent periods of overheating.

Further, modem closed systems, whether or not pped with flow control valves and a circulating pump and regardless'o'f how fired, are occasionally in dimculty because of haphazard methods of handling air and gas, including that trapped when the system is first filled and that liberated from the water when heated, and .the consequent air binding of some of the radiators or pipe lines. It has been customary, and largely because of thisair, problem, to use expansion I tanks which are larger than demanded by operating requirements.

In older types of hot water heating systems with their large radiators and piping and an open expansion tank at the highest point in the system, the handling of the air did not present a problem. The pipes and radiators were vented during filling and if some portion of one or more of the radiators afterwards developed air pockets. the operation of the system was disturbed very slightly. with the advent of the closed system, however, which enabled the use of higher water temperatures and the development of an efiicient, silent circulating pump which permitted the employment of smaller diameter piping, smaller radiators and the so-called convector heaters, the formation of air bubbles at different points in the system caused trouble. These bubbles may 1 form at the top of a convector or radiatoryfor example, and may partially or wholly prevent these units from acting as heat emitting agents and so reduce the emciency of the system. This blocking can occur even though the pump is operating and, in fact, I have determined that,

under these conditions, the weak circulation be- I tween the boiler and tank is suflicient to carry air bubbles from the tank to the radiators.

Air blocking is primarily due to a failure to correctly evaluate certain factors now inherent in a closed system, such as the trapping of a large amount of air in the expansion tank when the system is first filled, the retention of this air in the system, and the lack of provision for the 10% or more of air and othergases by volume which are released from the water during heating." I

have ascertained that this liberated air will not move upwardly through the water in the expansion tank, even when the pump is running, but, on the contrary, will pass to the. radiators, particularly those closest to the boiler, where it must be vented.

In view. of the foregoing, it is one object of my invention to devise a valveless flow control for a hot water heating system having a circusupply and return pipes, the so-calied one pipe system may be used without departing from the invention. In such a case, each radiator would be connected to the pipe l1, by the fitting dising of the boiler waterby permitting new to the 1,.

radiators when the pump is not operatingfthereby avoiding any necessity for a high limit, boiler aquastat 'and' its connection to the pump.

A further object is to devise a flow control as above in which provision is made for an easyand certain separation of theliberated air from the water and its collection in a closed tank to establish the deslged expansion factor.

A further object is the incorporation in a,va 1veless flow control having a water space always filled with water substantially at boiler tempera-s ture of meanslocated in the water space indirectly heating'service water.

A further object is to provide- 'a closed hot for water heating system of the iorced circulation type having a valveless flow controlinwhich the partsare arranged to insure that,- after the system is conditioned for operation, all "a'ir'in the" f system will be collected in the" expansion tank. a A further object is to devise an apparatus unit for a closed hot water heatingsys'tem having a circulating pump which embodies an expansion tank and a valveless fiow control so related that all air liberated from the water in passing through the boiler is trapped in the control in the tank. These and further objects of my invention will and collected be set forth in. the following specification, refer ence being had to the accompanying drawing, and the novel means by which said objects are eilectuated will be claims.

definitely pointed out'in the In the drawing:

Fig. 1 is a diagrammatic elevation,- partly in section, of a hot water heating system equipped with my improved valveless ping arrangement.

Fig. 2 shows a similar'system, but equipped control and airtrapwith a modified flow control which is arranged j for heating service water.

Fig, 3 is an elevation of an expansion tank, partly in section, in which is embodied a valveless flow control and air trapping structure.

Referring to Fig. 1, the numeral l0 diagrammatically represents a hot water heating boiler which may be hand or stoker fired and from the top of which extends a pipe ll into a casing l2, the pipe terminating short of the upper end of the casing '50 that, under certain conditions, water may flow from the pipe into the casing. As presently described, the pipe and casing constitute the valveless flow control for the system.

The upper end of the casing I2 is connected by a pipe It! with the upper portion of an expansion tank It having a manual vent ii for relieving air from the system under certain conditions.

. l'heilower portion of the tank is connected by a pipe It with the lower end-of the casing l2. Also connected to the lower part of the casing is one end-of a pipe l'lfor'supplying hot water to one or more radiatorslfl, from which the water is recirculated=to the boiler by a return pipe l9 which mayi'nclude a circulating pump 20. The

- pump is' driven by a motor 2l' forming part of an electric circuit 22 that includes a thermostat 23 positioned to be afiected by the radiator l8.- Instead of bridging the radiator between t e closed in United States Letters Patent No. 1,663,271.

Since one phase oi my invention is concerned with the elimination ofnunnecessary air from the system to prevent air .binding and to permit the use of a smaller expansion tank, reference will first be made to the method of conditioning,

the system in this respect for normal operation.

The' system is filled with water in the usual way and the.- air thus initially trapped in the radiators andany high points of the piping is vented; More importantly, the air trapped in the tank ll, as well as in the upper part of the casing l2, is'veiitedthrough the valve l5, thus removing, a primary cause of air pockets, so that before the boiler is fired, the system is com- 7 pletely filled with water and the onlyair in the system'is that contained in .thewater. The boiler is then fired, preferably with the pump out of operatiomfor a time sufilcient :to insure the ex- This pulsion of air from the waterin the boiler. air will freely separate from the water and will collect in the upper parts of the casing l2 and,

tank I 4' and is then vented through. the valve It, thus again filling the casing and tank with water.

pump 20 in' operation; so that as the water in the remainder of the system passes through the boiler, its containedair "is expelled and trapped in the upper portion of the casing I! to thereby form an air zone 24 above the surface of the I water therein'which is located below the upper end of the pipe H or generallyas-indicated by the numeral 25, and also an airzone 28 in the upper part of the tank I to accommodate expansion in the system. The system is now fully conditioned for operation. The air zone 24 constitutes a seal to prevent, as hereinafter described, thermogravitationai flow through the system since water in the casing .l2 and pipe ll,

tion of the air and the water permits the use of a considerably smaller expansion tank ior any given system than is now common practice.

' Moreover, the air expulsion renders the water air absorptive and therefore conditioned, to pick up small air bubbles that may cling to the surfaces in different portions of the system. This air is freed when the water passes through the boiler and is'trapped in the tank It and casing l2. Separation of air from the water in the pipe I i at all times is facilitated by the connection between the water spaces of the casing l2 and tank I 4 provided by the pipe I6 which is a feature of the invention. The pipe it permits displacement of water therethrough as air .is freed in the pipe II and so permits the separation of air from the water with a minimum of resistance, compared to the normal arrangement in which the expansion tank is connected to the boilr or radiatorsupply line by a single pipe.

Firing of the boiler is continued, but with the Y ace-8,856

open and the pump 20 therefore not running, thermogravitational flow of hot water tothe radiators is prevented by the air zone 24 unless the boiler is inadvertently overheated. With a pressure of say ten pounds in the system, the boiler water may be heated to a temperature of approximately 225 F. without setting up a gravity flow through the system. Above this temperature, however, the boiler water will surge intermittently through the pipe H into the casing l2 and will In the tank 50 and control may be generally relieve the excess heat to the radiators; The control therefore provides an automatic means of preventing overheating of the boiler and one that does not require a high limit boiler aquastat that is connected to the pump.

When the thermostat 23 demands heat, the pressure established by the pump 28 is suficient to force the water through the pipe ii into the casing l2, thereby providing a forced circulation through the system. In this connection, it

will be understood that the height of the pipe H above the water level therein is always capable of being overcome by the head of the pump. 1

The modification shown in Fig. 2 difiers from that illustrated in Fig. l in that the valveless flow 25 control 2lis arranged to heat service water. This control comprises a casing 26, corresponding to the casing id, but directly connected to the-boiler l 13 by a pipe 29. As in Fig. l. the upper and lower portions of the casing 28 are connected to the '30 corresponding portions of an expansion tanktd by pipes 3i and 32, respectively. The inlet end of a radiator supply pipe 33 is located within and close to the upper end of the casing 28, i. e.,

in the air zone 35, and passes downwardly 35 ternally connected to a cold water supply and bemused m the p p g to the ato e a storage tank (not shown). The diameter of the pipe 2a is large enough to insure a local circulation between the casing 28 and boiler when the pump 28 is not working, so that the casing is always filled with water substantially at boiler 59 water temperature. Otherwise, this system is arranged and operates in the same manner as that shown in Fig. l.

In the systems described above. the flow control and expansion tank are separateelements, 55

closed, except for certain connections present y noted. The container is internally divided by a wall 3t which may be insulated into an expansion tank 66 and a flow control Qt. The upper or air zones of the tank and flow control are connected by a passage t2, while the lower or water as zones are connected by a passage 3.

The flow control portion of the container is partially divided by a bafile M which extends upward from the bottom of the container and terminates short of the top thereof to form a cham- W ber which communicates with the upper portion of a boiler (not shown) by means of a pipe 66 and a chamber ti whose lower portion is connected to radiators (not shown) by a supply pipe 68. The chambers 45 and 47 communicate The with each other -m the upper "edge or the bafiie 44.

For purposes already noted,elimination of air v During non-pumping periods, the water level icated by the numeralislj ,Surging due to erheating of the boiler'may take place over the baflle 44, which is also surmounted during pump operation. The passages 42 and 43 insure free separation of air from'jthe water in the chamber 45 for reasons set forth above.

It is also contemplated that my improved flow control device may be employed in a gravity flow system which maybe identical with that shown in Fig. 1, except that the pump 20 is eliminated. In this case, when the boiler'is fired sumclently to raise the, temperature of the boiler water above 225 F., for example, the surge of hot water through the pipe M will carry heat to the radiators and at lower temperatures, no hot water will flow through the pipe I I. In stoker or oil fired Y boilers, control may be. exercised in the usual way by a room thermostat connected to the stokeror burner. The unit shown in Fig. 3 may also be I used in a gravity system.

I claim:

1. In a hot water heating system having one or more radiators, the combination of a boiler. a flow control device comprising an air trap and barrier means extending into the trap for preventing thermogravitational flow through the system, and a pump for forcing the water over the barrier means and through the trap to establish a circulation through the system.

2. In a hot water heating system having a radiator and a thermostat positioned to be affected thereby, the combination of a boiler, a flow control device comprising an air trap and a wall inextending into the trap for preventing thermogravitational flow through the system, and a pump responsive to the demand of the thermostat for heat for forcing the water over the wall and through the trap to establish a circulation through the system.

3. In a hot water heating system 'havingone or more radiators, the combination of a boiler, a flow control device having air entrapping means forming a seal for preventing thermogravitational flow through the system, and a pump for forcing water through the seal to establish a circulation through the system.

4. In a hot water heating system having one or more radiators, the combination of a boiler, a flow control device comprising two separate water chambers, one communicating directly with the boiler and the other with the radiators, and air entrapping means forming a seal'common to both chambers for preventing thermogravitational flow through the system, and a pump for forcing water through the seal to establish a circulation through the system.

5. In a hot water heating system having one or more radiators, the combination of a boiler. a flow control device comprising a pipe extending from the upper portion of theboiler, a casing surrounding the pipe and flow connected tn the radiators, and air entrapping means forming a seal common to the pipe and casing for preventing thermogravitational flow through the sys and a pump for forcing water through theseal to' establish acirculation through the system.

6. In a hot water heating system having one or more radiators, the combination of a boiler,

' thermogravitational, flow through the system, a

pump for forcing water through the seal to establish a circulation through the system, and a heat exchanging .device immersed in the first chamber for heating service water.

'7. In a hot water heating system having one or more radiators; the combination of a boiler, a flow control device having air entrapping means forming a seal for preventing thermogravitational fiow through the system, a pump for forcing water through the seal to establish a circulation through the system, and an expansion tank having a pipe connecting the air space thereof with the seal and -'a second pipe connecting the water space in the tank with the water in the system.

8. In a hot water heating system having one or more radiators, the combination of a boiler, a fiow control device comprising two separate water chambers, one communicating directly with the boiler and the other with the radiators, air entrapping means forming a seal common to both chambers for preventing thermogravitational flow through the system, a pump for forcing water through the seal to establish a circulation throughthe system,'and an expansion tank having a pipeconneoting the air space thereof with a the seal and a second pipe connecting the water space in the tank with the water in the system.

9. In a hot water heating system having one or more radiators, the combinationof a boiler, a flow control device comprising a pipe extending from the upper portion of the boiler, a casing surrounding the pipe and fiow connected to the radiators, and air entrapping means forming a seal common to the pipe and casing for preventing thermogravitational fiow through the system, a pump for forcing water through the seal to establish a circulation through the system, and an expansion tank having a pipe connecting the air space thereof with the seal and a second pipe connecting the water space in the tank with the water in the system.

amassc 1 air space thereof with the sealand a second pipe connecting the water space in the tank with the water in the system.

l2. Inaclosed hot water heating system having a boiler, one or more radiators, and a pump 'forcirculating water through the system, the combination of a device forming part of the supply line leading to the. radiators having first and second chambers, the first communicating directly with the boiler and always containing pipe connecting the air space thereof with the seal and a second pipe connecting the water space in the tank with the water in the system.

13. In a closed hot water heating system having a boiler, one or more. radiators, and a pump for circulating water through the system, a unit casing comprising an expansion chamber, a first water chamber communicating with the boiler, a. second water chamber communicating with the radiators, the water chambers constituting parts of the fiow path to the radiators, air entrapping means forming a seal common to both water chambers for preventing thermogravitational flow through the system but yielding to pump pressure for forced circulation, and pipes respectively connecting the air space of the expansion chamber with the seal and the water space of the expansion chamber with the first chamber.

14. In a closed hot .water heating system having one or more radiators, the combination of a boiler, a unit casing comprising an expansion chamber, a first water chamber communicating with the boiler, a second water chamber communicating with the radiators, the water cham- 10. In a closed hot water heating system having a boiler, one or more radiators, and a pump for circulating water through the system, the combination of a device forming part of the supply line leading to the radiators having air entrapping means forming a seal for preventing thermogravitational flow through the system, and an expansion tank having a pipe connecting the air space thereof with the seal and a second pipe connecting the ,water space in the tank with the water in the system.

11. In a closed but water heating system having a boiler, one or more radiators, and a pump for circulating water through the system, .the combination of a device forming part of the supply line leading to the radiators having two separate water chambers, one communicating directly .with the boiler and the other with the radiators, air entrapping means forming a seal common to both chambers for preventing thermobers constituting parts of the flow path to the radiators, air entrapping means forming a seal common to the water chambers for preventing thermogravitational flow through the system, pipes respectively connecting the air space of the expansion chamber with the seal and the water space of the expansion chamber with the first chamber, and a pump for forcing the water through the seal to establish a circulation through the system.

15. In a closed hot water heating system having a boiler, one or more radiators,'and a pump for circulating water through the system, the combination of a device forming part of the supply line leading to the radiators having first and second chambers, the first communicating directly with the boiler and always containing water substantially at boiler water temperature and the second with the radiators, air entrapping means forming a seal common to both chambers for preventing thermogravitational now through the system but yielding to pump pressure for forced circulation, and a heat exchanging device immersed in the first chamber for heating service water.

16. A valveless flow control device for a closed hot water heating system having one or more or more radiators. and a circulating pump comprising two separate water chambers, one chamber communicating directly with the boiler and the other with the-radiators, and air entrapping means forming a seal, common to both chambers for preventing thermogravitational flow through the system but yielding to pump pressure for forced circu1ation.- 1

18. A valveless flow control device for a closed hot water heating system having a boiler, one 10 or more radiators, and a circulating pump com-- prising a pipe adapted for connection to the upper portion of the boiler, a casing surrounding a the pipe and flow connected to the radiators, and air entrapping means forming a seal common to the pipe and casing for preventing thermogravitational flow through the system but ielding to pump pressure for forced circulation.

EDWIN B. TIDD. 

